Australian Patent No. 689324 (equivalent to U.S. Pat. No. 5,885,532) describes a medical burette that controls the flow from an intravenous liquid supply to the patient, while providing for the delivery of secondary liquids via a septum or the like.
The above device is complex in its structure and therefore is relatively expensive to manufacture.
A further disadvantage of the above discussed burette occurs when the burette is to be used to dispense a medication. In such a use, delivery of liquid from an IV bag is terminated. Liquid is still delivered from the burette until the outlet is closed. However when the outlet is closed there is still considerable residue liquid in the burette. The medication is then added with the effect that the medication is substantially diluted by the residue liquid. When the medication has been delivered and again the outlet closed by the drop in fluid in the burette, a significant portion of the medication is still retained in the burette. Accordingly not only is the medication diluted, but the full medication is not delivered.